Mechanically-operated furnace for roasting pyrites



MECHANICALLY OPERATED FURNACE FOR ROASTING PYRITES Filed June 29. 1921 s hee)s-Sheet 1 fig.

.Z'zvvgm I Zi.J'. GeScZwazi/nd Jan. 8, 1924. 1,480,525

L. J. GESCHWIND MECHANICALLY OPERATED FURNACE FDR ROASTING PYRITES Filed June 29. 1921 s Sheets-Sheet z Inversion L. =77 Gestdwanlnd,

Jan. 8, 1924. 1,480,525

L. J. GESCHWIND MECHANICALLY OPERATED FURNACE FOR ROASTING PYRITE Filed June 29, 1921 3 iheets-Sheet 5 I12 1161x3011 J. J. Geaclzmabzad;

" the rabbling rakes.

Patented Jan. 8, 1924. v

UNITED STATES PATENT onto n.

Lucian JosErH GEscnwI'Nn, onPARIsrRAivoE, nssrenoa To s'r i h fig en runns DE rnonurrs CHIMIQUES rnu NOR-D-ETABLISSEM'ENTS ZKUIHLMANN, or PAR-IS, FRANCE, A FRENCH :ooa-rona'riou. r

MEoHANIoALLY-oPEaArEn ruRNAoE Fort aoA's'r INGrYaIrEs.

Application flea-ma 29, 1921. Serial No; 481345.

To all whom it may concern:

Be it known that I, LUCIEN JOSEPH GESCHW'IND, a citizen of the French Republic, residing at ParisQ-France, have invented certain .new and useful Improvements in Mechanically Operated Furnaces for Roasting Pyrites, of which the following is a specification. y This invention relates to a mechanically operated furnace for roasting pyrites or like ores containing sulphur, of the known type comprising stationary soles and a central revoluble shaft, and afi'ording for a given surface of sole a roasting etfi'ciency which is much superior to that of the known fur naces. In order to obtain this result it is essential to make use of all the soles of the furnace to their maximum extent, this being secured by a feeding which is quite" constant and is adjustable according to the character of the materialemployed; as well as by a uniform distribution of the material over the various soles when starting from the first sole. The mass thus uniformly distributed is likewise required to'be roasted in a complete and uniform manner, and this can only be obtained by a rabbling which will not occasion an unduly rapid propulsion of the material and will also overturn the prismatic mass of the latter, besides leaving the different masses quite independent of each other during the process of roasting, each mass corresponding to the region of action of a tooth of the rabbling rake,

But up to the present time, the known devices have not been able to provide for a perfectly regular feed of the ore, chiefly by reason of frequent clogging or caking of the ore within the feeding hoppers, and furthermore, no special device was provided to secure the equal distribution of the ore upon the soles, as it was considered that this distribution was sufficiently afforded by However the various investigations which I have carried out relative to this subject have proved that such rakes possess but a small tangential reaction and that for this reason they are useful only as members for radial propulsion and not as distributing members. In fact, observations made upon the furnaces now in use lead to the :conclusion that it is only after the fourth sole that a reasonably good distribution is obtained; furthermore,lnone of the forms of rake hitherto proposed will afford the desired result as hereinbefore stated. 7

In the furnace'according tomy invention, these objects are attained in the following manner. by the use of an impact feeding device disposed at the bottom of a wide-mouthed'hop The feeding of the ore is effected per serving for the admission of thematerial and comprising an inclined movable-member adapted to receive the impact er a striker provided with a suitable adjustment for the amount, of swing and the frequency of the shocks. The shocks thus" produced are employed todis'charge the ore into th'e furnace, and fit is delivered upon the upper sole the ore is thus prevented from clogging at the discharge end of the.hopper,-as is p I the case with the known devices. To obtain a uniform distribution of the pyrites starta ing with, the first sole, the central shaft passing throughthe furnace from *top' to bottom has disposed upon the upper part T f a pair of inversely directed helical feeding'm'ough or 'spouts for receiving the stream ofore as delivered from the feeding device and for; distributing this ore'in a ring-shaped massfupon the upper sole whence it is caused todescend to'the succeeding soles.

The combined stirring and propulsion, or

the rabblingaction, carried out'upon each sole by means'of a singlerake or apair of oppositely situ ated rakes securedto the Mat 1 tral shaft and provided withqt'eeth having the form of a mould-board ofka plough which engages withxthemass of ore in an approximately vertical position, the disengaging angle 'beingsubstantially equal to the natural falling angle or bank of the pyrites. Furthermore, all the teeth secured either to a single rake or to a pair of oppositely situated rakes are so disposed as to follow each other inv a continuous series. thereby makinguse of thefentire sole. H

The furnace according to this invention likewise presents a number of character istic details of construction'which will be described hereunder. y

The accompanying drawingsshow by way of example an embodiment of my invention. Fig. 1 is a generalview of the furnace in section and elevation;

Fig. 2 is a View of the feeding device on a larger scale.

Figs. 3 and -4 are elevational and plan.

views of the device for distributing the 'pyrites upon theupper sole.

1 position of the teeth upon two oppositely situated rakes.

Figs. 8 and 9 are elevational and plan views of the helical passages provided in the walls of the furnace.

Figs. 10 and 11 are elevational and plan views of the gas passages provided in the walls of the furnace.

The furnace is constituted by a cylindrical chamber 1 having therein a series of stationary soles disposed in tiers, the bottom of each sole serving as a roof for the sole which is situated thereunder. A roof 3 is disposed above the upper sole. The chamber 1 is traversed throughout its entire height by a revoluble shaft 4 which is actuated by the shaft 5 through the intermediary of the drivingdevice 6. The speed of the driving may be modified and regulated by means of known devices which are not shown. The shaft 4 is provided above each sole within the constructional form represented as an arm 7 whose function will be described hereunder. In Fig. 1, only the inner ends of the said arms 7 have been represented, save for one of the, arms which is entirely shown.

The main gear wheel actuating the shaft 4 is provided with a flanged edge portion constructed of thin cast iron or sheet iron 41 which cooperates with the walls of the chamber 1 to form a trough for conducting into the discharge aperture 8 the roasted residues falling from the peripheral portion of the last sole. The air used for the purpose of facilitating combustion is admitted through the lowerpart of the furnace at 8. The feeding of the furnace with pyritesis effected at the top of the furnace in the following manner. The pyrites Figs, 1 and 2, are poured into the hopper 9 ending at the lower part thereof in a mouth of large section 10. The said hopperis disposed upon a closed casing 11, provided with a door 12 and a neck 1.3, and ending at the lower part in a spout 14 engaging the upper part of the chamber 1. Below the mouth 10 is disposed an inclined .movable member 15 which is strengthened at the rear part thereof by a thrust plate 16; the said movable member is suspended from thecasing 11 by fourarticulated links 17 which may be replaced without inconvenience-by rigid rods. neck 13 is traversedby an impact rod 18 whose head 19 is maintained upon its seat The said by a spring 20 the tension whereof is ad-l justable by means of the nut 21. A striking member 22 is pivoted at 23 to the hopper 9 and carries a rod 24 whereon are loosely'disposed the washers 25 forming a suitable weight and serving to regulate the said striker. A Wheel with four cams 26 rotating at slow speed provides forthe lifting and the sudden fall of the striker 22 upon the pyrites fall into one or the other of the two helical collars disposed in the contrary sense 27 28, and mounted upon the revoluble shaft, Figs- 3 and 4. The said collars form discharge spouts and are so constructed as to be readily removed. By reason of the rotation of the shaft, the pyrites will be fed upon the upper sole 2 in theform of a continuous and regular ring, which is acted upon by the rakes carried upon the arms 7. The soles 2 have the form which is shown in Fig. 1. The upper part thereof is constituted by a number of annular steps, the under part 30 being cone-shaped.

In order to provide a disposition wherein the said soles shall be situated in proximity to each other while at the same time giving to the said rake a suflicient height of teeth as Well as the amount of play which is required for its proper operation, the upper edge 31 of the arm 7 is made oblique and parallel to the generatrices of the cone 30. The stepped annular form which is given to the upper surface of the sole will provide a horizontal plane for the rabbling action without requiring the same thickness of sole which would be necessary if a plane upper surface were employed. The arm 7 actuated by the shaft 4 carries the rabbling rakes which move the pyrites from one level to the other in an alternate manner at the periphery and at the centre of the soles. The teeth of the said rake are therefore disposed alternately from one level to another in such manner as to afford respectively a centrifugal and a centripetal action, as is usual in furnaces of this class. In the constructional form represented in Figs. 1 and the said teeth, which are disposed parallel to each other by a method 'of construction shown in Fig. 5, is about 66,- in such manner as to obtain at the rear of the teeth a considerable spacing which will prevent clogging of the device. On the contrary to the arrangements hitherto employed, the teeth have the form of a mouldboard of a plough, as shown in plan and elevation in Fig.6. These teeth 32 attack almost vertically the mass of pyrites 47 (indicated in dotted lines) thrown back by the adjacent tooth and leave the mass at an angle which is substantially equal to the natural falling angle of the mass of pyrites, that is to say about 45. The teeth by turning over the mass 8 constitute by the side of the mass 8 another mass 9 which will be in turn treated by the following tooth. In this manner an efficient stirring action is obtained. The mass which is raised against the said-teeth is impelled in the forward direction; no falling slope or bank is formed'at the rear part, and the prism formed by the mass of pyrites is overturned at each of its points.

Moreover the masses of pyrites 'corresponding to each tooth will remain absolutely independent of each other during the process of roasting. It will be observed that this result cannot be attained by the use of known shapes of teeth which are. entirely fiat,'nor even with teeth in the form of a ploughshare acting after the manner of a spoon as has been proposed by some inventors. In fact with such teeth the mass of the pyrites is compressed between the blades and becomes raised up, and when leaving these members it rolls down in such manner that a portion of the material is covered by the banked material brought forward by the succeeding blade. This will give rise to a mixture of the masses which are in course of propulsion, and as the mass is not overturned, the mixing action will be defective, since by reason of the rolling down of the mass, the same particles will remain at the surface and at the centre. The teeth having the shape of a ploughshare will afford a slightly better stirring without obviating these drawbacks.

As the rakes which act in centrifugal direction are subjected to much greater resistance stresses than the rakes which act in centrifugal direct on, 1t lsadvantageous to give them a special form.

4 Instead of using a tooth of a triangular shape as is represented by the full lines in Fig. 6, it is preferable to give to its straight section on the sole a curve such as that shown in dotted lines. It is clear that when the tooth progresses in the direction of the arrow F, the resistance to forward movement is less for the curve 50 than for the straight line 49. In fact if this resistance is slightly higher for the curve towards the front part (if, the 1 curve, this in rease in asset-e is without great importance for in this part,-as can be seen by the elevation 8 of the mass of 'pyrites, the'penetration of the tooth is easily efl'eoted. On the contrary towards the rear, as the mass of 'pyrites displaced is greater, the curve 50b'ecomes' nearer than the straight line lgt'o the circumference about which is efi'ecte'd'the rotation'of each of its o'ints and consequently the resistance to rw'ard movement of this curve is less. The teeth of. rakes which act on a'c'entrip e'tal direction can be of much simpler formationas'long as theykeep the form of a mould boardof a plough which is the char acteristic of the system,- it is unnecessary to give them the curvature described above. Instead'of employing a single rake for each tier, two oppositely disposed rakes ma be employed which are provided with teeth of the same shape as herein describ'ed, but in this case the inclination of the said teeth with reference to the rake is only half What is used in the former case, and the teeth are alternately disposed upon one of the racks and the opposite rack, this arrangement being shown in Fig. 7. Y Upon the opposite arms 35 posed the teeth whereof the angle of inclination with reference to. the rake is onehalf the value of the inclination of the tooth 32 with reference to the rake 7, Fig. 5 Taking into consideration a tooth 37 disposed upon the rake 35, the end of the said tooth which is situated farthest from the centre of the furnace is located on the same circle as the end of the tooth 38 which is situated nearest ,-the' centre of the furnace, thislatter tooth being one of the set disposed upon the arm 36. In like manner, the end of this latter tooth which issitu'ated farthest from the centre of the furnace is located uponthe same circle as the end of the following tooth 39 carried by the rake which is situated nearest the centre of the furnace, and so on.

It will be observed that the results obtained by the arrangement shown in Figs. 1 and 5 are also obtained by the use of the above-mentioned device. Furthermore, instead of moving forwardly through a complete pitch distance for each revolution of the rake, the mass of pyrites moves forwardly by two operations to cover one-half the pitch distance at each operation. By this means a particularly efficacious roasting of the ore is obtained. Moreover, in the case of ores having a tendency to'agglomerate by melt ing, this will afford a means for breaking the crust which is formed. On the other hand, by reason of the lesser inclination of the teeth, the effect of clogging is obviated to a considerable degree. To reduce to a minimum the amount of dust given off during the descent of the pyrites, this dust til ioo

being prejudical to the proper roasting, the following device has been provided for the downward movement at the periphery. The odd numbered soles 2 are provided with the incline planes 40, Figs. 8-and 9, which are suitably spaced around the periphery; within the walls of the chamber 1 are formed the helical passages 12 opening opposite the said inclined planes for conducting the material to the sole situated immediately thereunder, a raised portion 43 being provided upon the periphery of the latter in such manner as to form a triangular prism constituted by the falling of the material and the rake under centripetal action at this level is caused to engage with the said material. The passages 44- passing through the wall of the chamber 1 are used to clear out the said passages 42, should this be required.

To convey the material from an even numbered sole to an odd numbered sole situated immediately thereunder, the even numbered sole has formed at the centre a funnel-shaped aperture 45. An arrangement may likewise be employed for dust-reducing purposes wherein suitable passages are disposed oppositethe said apertures 45 on the shaft 4 for conducting the pyrites to the lower sole. In order to prevent hot gases rising through the furnace from passing through and drawing along the dust, a separate path isafforded forthe same, as is already known. To this effect the walls of the chamber 1 have disposed therein the passages 46 which are caused to open at a higher level than the opening of the helical passages 42. The said passages constitute a path of least resistance for the ases which will have a strong flow throug the same and will therefore be prevented from passing'through the dust.

What I claim is:

1. In a furnace mechanism for roasting pyrites, having fixed stepped hearths, a

central rotating shaft and a rake carried by the shaft, teeth carried by the rake being in the form of plough mold boards.

2. A mechanically operated furnace for roasting pyrites provided with stationary soles disposed in tiers and a central revoluble shaft having mounted thereon the rabbling rakes, a wide-mouthed hopper, a closed receptacle supporting the said hopper and entering the upper part of the furnace, a laterally movable member disposed in an inclined position under the discharge aperture of the said hopper, a striker acting upon the said movable member, a hammer actuating the said striker, a cam shaft controlling the swing of the said hammer, a device for adjusting the weight of the said hammer, a device for the regular distribution of ore upon the first sole of the furnace, rabbling arms provided at each tier, and teeth having the shape of the mould boa-rd of a plough, the

said teeth being situated paralell to each other in a continuous row and obliquely disposed with reference to the arm.

3. A mechanically operated furnace for roasting pyrites provided with stationary soles disposed in tiers and a central revoluble shaft having mounted thereon the rabbling rakes, comprising in combination a device for regular and adjustable feeding which is actuated by the effect of shocks, a double helical spout disposed upon the central shaft between the feeding device and the upper sole, rabbling arms provided at each tier, and teeth having the shape of the mould board of a plough, the said teeth'being situated parallel to each other in a continuous row and obliquely disposed with referenceto the arm.

4. A mechanically operated furnace for roasting pyrites provided with stationary soles disposed in tiers and a central revoluble shaft having mounted thereon the rabbling rakes, comprising in combination a device for regular and adjustable'feeding which is actuated by the effect of shocks, a device for the regular distribution of ore upon the first sole of the furnace, two oppositely-directed rabbling arms disposed at each tier and teeth having the shape of the mould board of a plough, the said teeth being situated parallel to each other in a continuous row and obliquely disposed with reference to the arms, and so arranged that for a given tooth carried by one of the said rakes, the end of the said tooth which is situated farthest from the centre of the furnace shall be located on the same circle as the end nearest the centre of the furnace of the following tooth of the oppositely situated rake, and

so on.

5. A mechanically operated furnace for roasting pyrites provided with stationary soles disposed in tiers and a central revoluble shaft having mounted thereon the rabbling rakes, a wide-mouthed hopper, a closed receptacle supporting the said hopper and entering the upper part of the furnace, a laterally movable member disposed in an inclined position under the discharge aperture of the said hopper, a striker acting upon the said movable member, a hammer actu-= ating the said striker, a cam shaft controlling the swing of the said hammer, a device for adjusting the weight of the said hammer, a double helical spout disposed upon the central shaft between the inclined laterally movable device and the first sole of the furnace, two oppositely-directed rabbling arms disposed at each tier and teeth having the shape of the mould board of a plough, the said teeth being situated parallel to each other in a continuous row and obliquely disposed with reference to the arms and so arranged that for a giventooth carried by one of the said rakes, the end of the said tooth which is situated farthest from the centre of the furnace shall be located on the same circle as the end nearest the centre of the furnace of the following tooth of the oppositely situated rake, and so on.

6. A mechanically operated furnace for roasting pyrites provided with stationary soles disposed in tiers and a central revoluble shaft having mounted thereon the rabbling rakes a wide-mouthed hopper, a closed receptacle supporting the said hopper and entering the upper part of the furnace, a laterally movable member disposed in an inclined position under the discharge aperture of the said hopper, a striker acting upon the said movable member, a hammer actuating the said striker, a cam shaft controlling the swing of the said hammer, a device for adjustin the weight of the said hammer, a doub e helical spout disposed upon the central shaft between the inclined 1aterally movable device and the first sole of the furnace, two oppositely-directed rabbling arms disposed at each tier and teeth having the shape of the mould board of a plough,

the said teeth being situated parallel to each the furnace of the following tooth of the oppositely situated rake, and so on, and helical spouts provided in the walls of the furnace for the lateral descent'of the pyrites from one tier to another.

In Witness whereof I have hereunto set my hand.

LUGIEN JOSEPH GESCHWIND. 

